This is a proposal to establish and characterize an adult canine model for the study of treated and untreated bladder outflow obstruction caused by hormonally induced prostatic hyperplasia. The only mammals in which benign prostatic hyperplasia spontaneously occurs are man and dog. For this reason, the canine prostate has been an excellent model for studying the hormonal basis of prostatic growth and hyperplasia. In man, the leading causes of morbidity from prostatic enlargement are due to bladder outlet obstruction. In the dog, these symptoms have not been produced because the dog lacks a capsule similar to man. Investigators have thus been unable to study the effects of gradual obstruction in a mature or senescent mammalian model. We propose to establish a model of bladder outlet obstruction as close to the human condition as possible. A surgical capsule will be implanted around the canine prostate to provide maximum anatomical similarity of the human situation. The prostate will be subjected to controlled hormonal stimulation to produce gradual growth and obstruction. The effects of obstruction on organ appearance, performance and composition will be evaluated by means of urodynamic, cystoscopic, histological and biochemical study. Finally, the effects of treatment, by removal of the capsule and the obstructing prostate, will be evaluated.